1. Field of the Invention
The present invention relates to a magnetic levitation actuator which levitates and supports an object to be driven, such as an optical head and also relates to a magnetic actuator which linearly moves the optical head.
2. Description of Related Art
In known optical disc devices such as, for example, a laser disc device, a compact disc device, or an optical recording and reproducing system, an optical head for recording and/or reproducing data is moved in a radial direction of an optical disc (circular disc-like recording medium) by a drive mechanism. As is well known, the optical head emits a recording or reproducing laser beam, so that upon recording, an array of small record (signal) holes are formed on the recording medium (optical disc), and upon reproducing, the recorded data is read, based on light reflected from the signal hole array. The optical head is usually supported by a magnetic levitation actuator.
The magnetic levitation actuator is theoretically comprised of a pair of magnetic attraction circuits (or magnetic repellent circuits) positioned between guide rails which extend in the radial direction of the optical disc and the optical head. The optical head is levitated in the air in a non-contact state due to a balanced magnetic attractive or repellent force of the magnetic attraction circuits (or the magnetic repellent circuits). However, in the known magnetic levitation actuator the magnetic attractive or repellent force is small so that the supporting force of the optical head is insufficient to resist an external turbulence, such as vibration or the like. Consequently, the optical head may fall.
Furthermore, it is necessary to provide a tracking device in order to move the optical head in the radial direction of the optical disc. However, a known tracking device, usually comprised of a magnetic driving device, is provided separately from the magnetic levitation actuator for levitating and supporting the optical head as mentioned above. This is one obstacle in the realization of a small apparatus.